This invention relates generally to balanced pressure underwater acoustic projectors, and more particularly to a pneumatically powered, ultra low frequency acoustic signal generator for submerged use.
Underwater acoustic energy projectors find use in a variety of applications, both military and scientific. Such projectors generally comprise an acoustic signal generator housed in a towed body and are required to operate at great depths of submergence. Moreover, they require considerable power to deliver the desired acoustical energy into the water at those depths. In order to obtain maximum efficiency of operation of the signal generator, it has been the practice to provide a pressure system that will maintain an equilibrium between the signal generator and the ambient hydrostatic pressure irrespective of changes in operating depth throughout a considerable range of depths. A particularly effective pressure equilibrium system is disclosed in U.S. Pat. No. 3,803,544 to Albert E. Wallen, et al.
The acoustic signal generators employed in such towed projectors have generally been of the electroacoustic type utilizing piezoelectric electromagnetic transducers. These have achieved notable success through a wide range of frequencies, although size and structural considerations renders them less satisfactory as frequencies decrease and as hydrostatic pressures increase.